EMERGENCY is past due but I need to finish it question- In a certain chemical, the ratio of zinc to copper is 4 to 15. A jar of the chemical contains 390 grams of copper. How many grams of zinc does it contain?

This is what i found “an explicit formula designates the nth term of the sequence, as an expression of n (where n = the term's location). it defines the sequence as a formula in terms of n. this example is an arithmetic sequence(the same number, 5, is added to each term to get to the next term).” i hope this you for what your looking for. can you plz mark me brainliest?